An increasing number of devices are being made available in portable form, such as mobile telephones, personal digital assistants, music players, pagers and so on. Such devices typically include a power supply, in the form of a battery. However, as the power that can be provided by a battery is limited, the device must allow recharging and/or replacement of its battery. Therefore, many devices include sockets for receiving a connector for charging the battery and/or are configured to permit access to a battery compartment. In addition, such devices may include other components that are accessible from the exterior of the device, such as displays and keypads of a user interface.
However, where a device is required to be waterproof, the provision of such sockets or accessible components may compromise the degree to which the ingress of water into the device can be prevented. This problem is particularly relevant to, but not limited to, wearable electronic devices. As a consequence of their wearable nature, these devices may be subjected to a variety of environmental conditions, including rain.
While it may be possible to provide a mechanical valve for preventing water ingress around a component such as a socket, display or keypad, such a solution would be expensive, complex and prone to failure.
Another option would be to provide a resilient gasket. The water tightness of the device can then be ensured by maintaining the gasket under pressure to provide a seal. Such a gasket would again be expensive, while being difficult to manufacture. Furthermore, over time, the material of the gasket could harden, reducing its effectiveness. Where a gasket is provided over a socket, the user may be required to manipulate it in order to gain access, which may be inconvenient and potentially cause damage to the gasket.
Another potential solution, in the case of sockets, relies on the use of conductive plastics. Such materials can be injection moulded to provide a seal around electrical components. However, the resistance of such plastics remains relatively high. Consequently, the time required to charge a battery may be lengthy and, thus, inconvenient to a user. Moreover, the plastic material may be subjected to high temperatures, increasing the chance of mechanical failure.